There are multiple ambiguities, and, as always, they are impossible to resolve without knowing the precise context or hearing the intonation of the speaker.

The bigger ambiguity is related to the meaning of "so much". I can see two entirely different interpretations:

I recently experienced an event with a huge amount of pain. The last time I experienced that amount of pain was when I was in the Army.

I suffer from constant pain. The pain has not been so severe since I left the army.

But in a real-life situation with real speakers, the ambiguity you raise and the one I raise simply do not arise. It is not that the context resolves the ambiguity, but rather that it simply does not arise.

The response to virtually every one of your posts is identical, namely yes, the examples you give are ambiguous because you have designed them to be so, but that they would not be ambiguous in a real-life situation.

There is a limit to the number of times that we can keep on saying the same thing.

One interesting aspect of the answer to the repetitive question is that, given the chance to intonate audibly the sentences, one could obviate the question of meaning and vaporize any ambiguity.
The limitation of print leads some to add indicators like "/s" to their scrawls.